Clinical evaluation and laboratory investigation of unusual or unsolved dermatologic problems. Often involved are heritable diseases; heightened susceptability to cutaneous DNA damage; trauma or infection. Skin cancer. Skin biopsies taken for studies of morphology and to establish cultures of cutaneous fibroblasts, melanocytes and epidermal cells; karyotyping and evaluation of chromosomal damage. Assessing lichen planus, mycosis fungoides, lupus erythematosus, photosensitivity disorders.